<!DOCTYPE html>
<html>
  <head>
    <title>按钮效果</title>
    <style>
      body {
        margin: 0;
        padding: 0;
        background: #000;
      }
      .blur-btn {
        position: absolute;
        top: 50%;
        left: 50%;
        transform: translate(-50%, -50%);
        width: 200px;
        height: 60px;
        line-height: 60px;
        font-size: 24px;
        text-transform: uppercase;
        text-decoration: none;
        font-family: sans-serif;
        text-align: center;
        color: #fff;
        box-sizing: border-box;
        background: linear-gradient(90deg, #03a9f4, #f441a5, #ffeb3b, #03a9f4);
        background-size: 400%;
        border-radius: 30px;
      }
      .blur-btn:hover {
        animation: animate 5s linear infinite;
      }
      @keyframes animate {
        0% {
          background-position: 0%;
        }
        100% {
          background-position: 300%;
        }
      }
      .blur-btn:before {
        content: "";
        position: absolute;
        width: 105%;
        top: -5px;
        right: -5px;
        bottom: -5px;
        z-index: -1;
        background: linear-gradient(90deg, #03a9f4, #f441a5, #ffeb3b, #03a9f4);
        background-size: 400%;
        border-radius: 40px;
        opacity: 0;
        transition: 0.5%;
      }
      .blur-btn:hover:before {
        filter: blur(15px);
        opacity: 1;
        animation: animate 5s linear infinite;
      }
    </style>
  </head>
  <body>
    <!-- ONLINE TUTORIAL  -->
    <a class="blur-btn" href="#">Button</a>
  </body>
</html>
